Tale of a two-tailed virus
Author: Natural History

With waters at least ten times more acidic than vinegar, and scorching temperatures as high as 200 degrees Fahrenheit, the hot springs of Pozzuoli, in southern Italy, are a special place to live. It's a good bet that any life-form that can survive in such conditions would have evolved some unique adaptations. Now Monika Haring, a molecular biologist at the Pasteur Institute in Paris, and several collaborators have discovered a remarkable adaptation in a virus from Pozzuoli: the organism can grow parts of its anatomy on its own, independent of its host cell.

No virus previously studied can grow or reproduce without the chemical building blocks and genetic copying machinery it commandeers from the cell it infects. But Haring's virus, dubbed Acidianus two-tailed virus, or ATV, is a bit more autonomous. The virus grows inside a member of the diverse and largely unexamined group of microorganisms called Archaea. ATV destroys its host cell after it has reproduced; once outside in the harsh spring water, it sprouts two tails all by itself.

Haring's group detected a gene in ATV that is also present in other organisms, where the gene codes for a filament-forming protein. The same filaments likely make up the virus's two tails. What the tails do is uncertain, however. They may stabilize ATV's structure in the hot, acidic water. Or, since ATV destroys its host, the tails may help the virus reach the few other, widely dispersed potential hosts that roam the hot springs. (Nature 436:1101-1102, 2005)